Process for the raster-formed coating of web-shaped flexible flat articles with hot-melt adhesives

Abstract

This invention describes a process and an apparatus for the raster-formed coating of web-shaped flexible flat articles (3) with hot-melt adhesives in a screen printing process by filling all perforations of a rotary screen printing stencil (1) by means of an outer blade (6) with a solution or dispersion of a paste (2), by placing the flat article (2) on the rotary screen printing stencil (1) and by subsequently additionally applying a paste (5) by means of an inner blade (4). On the finished product, paste (2) produces a plastic base layer which is not or only slightly capable of thermal activation and paste (5) produces a hot-melt adhesive top layer which is easily capable of being thermally activated. Following the drying and sintering of the double-layered printed flat article (8), it can be used as an attachable inlay material for items of clothing.

I claim: 
     
       1. A process of raster-formed coating of web-shaped flexible flat articles comprising inlay materials for clothing items with hot-melt adhesives in a screen printing process by applying two superimposed raster-formed paste layers on the finished product, consisting of a base layer which is not or only slightly capable of thermal activation and and a hot-melt adhesive layer superimposed thereon which is capable of thermal activation and has a higher state of fusion than the base layer through of two sequentially implemented coating steps; comprising a first said coating step of wiping a paste (2) of a dispersion of a plastic mass not or only slightly capable of thermal activation with a blade into perforations of a rotary screen printing stencil (1) from the outer side of said stencil so as to fill each perforation; bringing the rotary screen printing stencil (1) thereafter into contact with the flat article (3) and, in addition to the externally applied paste (2), a second said coating step comprising printing by wiping into the perforations through an inner blade (4) a further paste (5) which forms the hot-melt adhesive mass capable of thermal activation, and thereafter implementing a drying and sintering of the double-layered print after releasing the printed flat article (8) from the rotary screen printing stencil. 
     
     
       2. A process in accordance to claim 1, wherein a partial filling of all perforations of the rotary screen printing stencil (1) is implemented with paste from the outside through a blade (6) arranged on the outer side of the stencil, a stroking edge of the blade being ground to be sharp and being arranged on the rotary screen printing stencil (1) at an obtuse angle of 120° to 150° relative to the stencil wall on the side of the paste feed (2) so as to effect the filling of all perforations in a scooping action. 
     
     
       3. A process according to claim 2, wherein the filling of the stencil perforations from the outside is implemented with a supporting apparatus (7) lying against the inner side under the line of contact between the stencil and the outer blade (6), the supporting apparatus extending across the entire width of the rotary screen printing stencil (1) and conforming at the inner curvature of the stencil (1) to the stencil (1) inner wall through two blade plates (7a) arranged closely adjacent each other and at an angle under the stencil apex. 
     
     
       4. A process according to claim 2, wherein the coating paste (2) applied as a base layer is selected from the group of materials consisting of polyurethene, polyacrylate, polybutadene-acrylonitrile, polybutadene-styrene-acrylonitrale and acetate copolymers. 
     
     
       5. A process according to claim 1, wherein the outer coating paste (2) includes fine granulate powder which is selected from the group of materials consisting of hot-melt adhesives, PVC, mineral fillers and, additionally, fatty-acid salts, softeners, thickeners, coagulates, paraffins and waxes. 
     
     
       6. A process according to claim 1, wherein the hot-melt adhesive paste (5) applied with the inner blade (4) is selected from the group of materials consisting of copolyamides, copolyesters, low-pressure polyethylenes and polyurethanes. 
     
     
       7. A process according to claim 1, wherein the outer coating is implemented on a rotary screen printing stencil (1) having an outer side which is ground down to a smooth surface finish.